In the assembly of magazines, newspapers, booklets, and the like, collating machines are broadly used to gather, in sequential order, the several pages comprising the particular publication. The pages so gathered generally are printed as "signatures", with each signature being a single sheet of paper folded once along its midline to create two leaves. These signatures are then gathered in sequential order within each other along respective fold lines to yield a folded stack of paper, such as, a magazine which can be stitched if desired along the fold line.
As is appreciated by both the collator operator and the ultimate reader of a publication so assembled, it is imperative that no signature be missed during the collating process. Assuming each signature is printed on both sides of both leaves thereof, the absence of only one such signature obviously results in the absence of four pages from a publication so assembled. Thus, only a singular miss of a signature by a collating apparatus can result in an unreadable, and necessarily discarded, publication.
It is therefore apparent that a need is present for a collating machine which possesses fail-safe provisions in regard to non-inclusion of a signature, and which is highly reliable and efficient requiring a minimum number of steps in operation.
Representative of this approach are disclosed in U.S. Pat. Nos. 1,043,401 to S. C. Cox; 2,709,584 to J. Kleinberg; and 2,817,513 to D. T. Bell et al. Of these patents, Cox is of interest for disclosing a method and apparatus wherein the signatures are opened by a vacuum and a pusher rod is advanced between successive signatures for assembling into a magazine, book or the like. Kleinberg discloses a similar type of pivotal valve operation and vacuum system. Bell's device is provided with pivotal suction of vacuum heads for disposing signatures in the path of a collector arm, the pivotal movement of the arm actuating a valve to relieve the vacuum when the signature has been collected. Other patents of general interest in the field are U.S. Pat. Nos. 3,069,025 to R. Winkler et al; 3,372,924 to E. H. Treff; and 3,547,429 and 3,572,683 to R. Hepp. Winkler et al discloses a specific type of rotary valve arrangement to control the application of vacuum in forming blanks into envelopes wherein the valve is adapted to control application of vacuum during selected period of time in the course of revolution of the valve. The Treff patent illustrates yet another type of valve arrangement wherein the vacuum is periodically relieved at timed intervals in response to movement of a sheet past a vacuum port. The Hepp patents are further illustrations of utilization of suction in spreading signatures for collating systems wherein spreading rollers are employed for collecting the signatures.